Primary Spontaneous Pneumothorax

Air in the pleural space without trauma and without clinically obvious lung disease. Incidence is about 7 to 18 per 100,000 per year in men and 1 to 6 per 100,000 in women. It peaks at age 15 to 35 in tall, thin men and is uncommon after 40.

• Mechanism: rupture of subpleural apical blebs or bullae (found at surgery in about 85 to 90%), usually on a background of small airway inflammation in smokers.
• Risk factors: smoking (risk rises about 9-fold in light and up to 20-fold in heavy male smokers, in proportion to dose), cannabis smoking, tall stature, family history (including Birt-Hogg-Dube syndrome with FLCN variants), and changes in atmospheric pressure.
• Recurrence is about 30% within 1 to 2 years (mostly in the first year) and 50% or more after a second episode. Death is rare, and tension physiology occurs in about 1 to 2%.
• Size: small is a rim of air less than 2 cm between lung edge and chest wall at the level of the hilum, and large is 2 cm or more.

• Sudden one sided pleuritic chest pain and breathlessness, often at rest, usually mild and often settling within 24 hours even when air remains.
• Signs: reduced expansion, hyperresonance, reduced breath sounds, tachycardia. Tension: severe distress, hypotension, tracheal deviation away from the side, distended neck veins, cyanosis.
• Differential diagnosis: secondary pneumothorax (older patient, underlying lung disease), pulmonary embolism, pericarditis, pneumonia, myocardial infarction, aortic dissection, oesophageal rupture, pneumomediastinum, large bulla, diaphragmatic hernia, musculoskeletal pain, and catamenial thoracic endometriosis in women (right sided, within 72 hours of menses).
• Complications: tension pneumothorax, persistent air leak beyond 5 to 7 days (about 5%), recurrence, haemopneumothorax (about 2 to 5%, from a torn adhesion vessel), re-expansion pulmonary oedema (about 1% after rapid drainage), bilateral pneumothorax, empyema after drainage, and post-pleurodesis pain.

• Erect PA chest X-ray: visceral pleural line with absent lung markings beyond it. Do not delay treatment for imaging in tension pneumothorax.
• Bedside ultrasound (absent lung sliding, absent B lines, lung point; sensitivity about 90%) is useful in the emergency room.
• CT chest when X-ray is unclear (bulla versus pneumothorax), for persistent leak, for recurrence, or to look for blebs and cystic disease (lymphangioleiomyomatosis, Langerhans cell histiocytosis, Birt-Hogg-Dube cysts).
• SpO2 in all, arterial blood gas if hypoxic, ECG if pain is atypical, pregnancy test in women of childbearing age, HIV test, and alpha-1 antitrypsin level in recurrent or basal disease.
• Genetic referral for recurrent or familial disease, lung cysts, skin fibrofolliculomas or renal tumours.

• Tension pneumothorax (clinical diagnosis, treat at once):
  • Oxygen 15 L/min by mask. Needle decompression with a 14 gauge cannula at least 5 cm long (8 cm in large patients) in the fifth intercostal space just in front of the mid-axillary line (or the second space in the mid-clavicular line), followed at once by a chest drain.
• Simple pneumothorax, by size and symptoms:
  • Small (less than 2 cm) and minimally breathless: observe as an outpatient, with review in 2 to 4 days and a repeat X-ray at 2 to 4 weeks. Air is absorbed at about 1.25 to 2.2% of the hemithorax per day. Advise to return if breathlessness worsens.
  • Oxygen 10 L/min by mask speeds absorption about 4-fold in inpatients.
  • Large (2 cm or more) or breathless: needle aspiration with a 16 to 18 gauge cannula (or 8 to 12 French catheter) in the second intercostal space mid-clavicular line, withdrawing up to 2.5 L and stopping if resistance or cough occurs. Success is about 60 to 70% at the first attempt. Repeat once; if it fails, insert a drain.
  • Chest drain: small bore 8 to 14 French by the Seldinger technique in the safe triangle (between the anterior border of latissimus dorsi, the lateral border of pectoralis major and a horizontal line at the level of the nipple, fifth intercostal space), connected to an underwater seal or one way ambulatory valve. Do not apply suction at first; if the lung has not re-expanded by 48 hours, apply high volume low pressure suction at 10 to 20 cmH2O. Never clamp a bubbling drain. Remove it when there is no bubbling for 24 hours and the lung is fully expanded on X-ray.
  • Re-expansion pulmonary oedema: avoid early suction and draining more than 1.5 L at once; if cough or chest tightness develops, clamp the drain for 1 hour and give oxygen, with diuretic or continuous positive airway pressure if severe.
  • Analgesia: paracetamol 1 g four times daily, ibuprofen 400 mg three times daily with food, and morphine 2.5 to 5 mg IV or orally for severe pain.
• Definitive treatment (video assisted thoracoscopic stapled bullectomy or blebectomy with pleurodesis) for:
  • Persistent air leak beyond 5 to 7 days, or failure of the lung to re-expand.
  • Second ipsilateral episode, first contralateral episode, bilateral episode, or spontaneous haemothorax.
  • Occupations with high risk (pilots, divers) and patients living far from care.
  • Patient preference after a first episode.
  • Results: recurrence falls from about 30% to 2 to 5% after surgical pleurodesis (mechanical abrasion, partial pleurectomy, or talc poudrage 2 to 5 g). Recurrence is about 25 to 50% with drainage alone.
  • For patients unfit for surgery: talc slurry 4 to 5 g in 50 mL saline through the drain after intrapleural lidocaine 3 mg/kg (maximum 250 mg) and systemic analgesia; autologous blood patch 1 to 2 mL/kg through the drain for persistent leak (evidence is limited).
• Advice at discharge: stop smoking (varenicline 0.5 mg daily for 3 days, 0.5 mg twice daily for 4 days, then 1 mg twice daily for 12 weeks, or nicotine patch 21 mg/24 h), avoid flying until resolution is confirmed on X-ray and for at least 1 week afterwards (2 to 4 weeks after surgery), avoid diving permanently unless definitive surgery has been done and specialist assessment is satisfactory, and return urgently if symptoms recur.
• Special groups:
  • Pregnancy: aspirate with a 16 to 18 gauge cannula or place an 8 to 14 French drain; recurrence in later pregnancy is common; plan delivery with an assisted second stage and avoid prolonged Valsalva; defer surgery until after delivery unless there is persistent leak.
  • Children and adolescents: small bore drains sized by age (8 to 12 French); early thoracoscopy for persistent leak.
  • Catamenial pneumothorax: surgery with diaphragm repair and pleurodesis, then hormonal suppression with goserelin 3.6 mg SC every 28 days for 6 months (evidence is limited).
  • Birt-Hogg-Dube syndrome: yearly renal MRI for tumours.
• Red flags: haemodynamic instability, SpO2 less than 90%, bilateral disease, drain bubbling beyond 5 to 7 days, subcutaneous emphysema extending, large haemothorax.
• Follow up: review at 1 to 2 weeks and 4 to 6 weeks with chest X-ray; counsel about the 30% recurrence risk; yearly review in familial disease.